Not Applicable
Not Applicable.
This invention relates to dental prophylaxis angles. It has particular, although not exclusive, application to disposable dental prophylaxis angles.
Commercial embodiments of the disposable dental prophylaxis angles disclosed in Bailey, U.S. Pat. No. 5,328,369, which is incorporated herein by reference, and particularly the embodiments of FIGS. 1-5 and 7-8 of the noted Bailey patent, have been successfully sold by Young Dental Manufacturing Company of Earth City, Mo. for several years. Until the present invention, these angles have included the finger 53 on the cap and the groove 55 in the drive gear shaft for the purpose of controlling end play (excessive forward movement) of the drive shaft.
Other approaches to controlling end play of the drive shaft have been used. Thiedemann et al., U.S. Pat. No. 1,534,817, Graham, U.S. Pat. No. 3,727,313, and Warden et al., U.S. Pat. No. 4,266,933 have allowed the forward end of the drive gear to abut the shaft of the driven gear in order to limit end play. Kraenzle, U.S. Pat. No. 6,203,322, sizes a portion of the shaft of his driven gear for continuous engagement by a flat surface at the forward end of the drive shaft over a substantial area of the flat surface to limit the forward movement of the drive shaft. Commercial devices made in accordance with Graham, U.S. Pat. No. 3,727,313 include a short post, with a central opening extending deeply into the drive shaft, at the forward end of the drive gear.
All of these modified angles suffer from requiring a large area of contact between the drive gear or extension post and the shaft of the driven gear. This large contact area increases friction and makes lubricating the moving parts more difficult.
Briefly stated, a dental prophylaxis angle of the present invention includes a body having a sleeve, a neck at the end of the sleeve, and a head formation at the end of the neck. A chamber is formed in the head formation and a passage extends through the neck and sleeve and is in communication with the head formation chamber. The sleeve is sized to fit the nose of a dental handpiece.
The dental angle includes a drive part having a drive shaft which extends through the neck and sleeve passage, a drive member near the forward end of the drive shaft, and a post extending from the forward surface of the drive member. The drive part shaft has an axis of rotation and is sized for gripping by a gripping mechanism in the handpiece.
The post has a cavity formed in a forward surface thereof. The cavity can be filled with a lubricant. The drive part post cavity is defined in part by a peripheral wall of the post. The cavity can have a generally concave surface. Alternatively, the cavity can be defined by a generally cylindrical wall and a bottom surface. Preferably, the drive part post has a height approximately equal about 5% to about 30% of the height of the drive gear (from the back surface of the drive gear to the forward surface of the drive gear).
The dental angle also includes a driven part which is received in the head formation chamber. The driven part includes a driven part shaft, a driven member, and a post to which a dental tool can be mounted. The driven member engages the drive member, such that the driven part is rotated by rotation of the drive part. The driven part has an axis of rotation at a substantial angle to the axis of rotation of the drive part.
The neck ends in a shoulder, and the drive member is sized to limit rearward movement of the drive shaft. Additionally, the drive part post is sized to limit end play of the drive part.
The driven part post has a length such that thrust loads are passed through the driven part shaft and borne by the angle body, rather than by the angle gears. To accomplish this, the length of the driven part shaft is about 11% to about 15% greater than the drive gear diameter.
Preferably, the drive part and the driven part are molded of plastic.